Understanding and Controlling Electronic Transport via Proteins: Nanoscale Electrode Architecture-enabled Energy Level Alignment

在这个项目中，我们想要回答“门控如何控制蛋白质之间电子传递的效率和机制？”这个问题。关于几种蛋白质的电荷转移过程已经积累了许多知识和理解。人们对固体型连接中蛋白质的电荷传输也越来越感兴趣。尽管如此，关于什么是非常有效的电荷输运及其温度依赖性，仍然存在一些非常重要的开放性问题，这些问题直接影响到潜在的输运机制。正如其他电子领域所知，在固态结构中使用第三电极可以控制电荷传输的静电“门控”（如场效应晶体管）。寻找可重复添加门控的方法将是回答这些悬而未决的问题和解开蛋白质之间的电子-电子传递的重要一步。有了栅极后，蛋白质分子的电子能级分布可以沿着导联费米能级的方向移动，从而与相应的输运过程相关联。我们打算通过实现高掺杂硅触点的不同架构来实现上述目标，从而在技术上解决传输机制的基本问题，这些触点相距几个~ 10nm，只有（纳米间隙电极），并且具有近距离的栅极。我们将选择合适的蛋白质系统，并在与电极相同材料的平面表面上彻底表征这些蛋白质系统后，纳米间隙将被这些蛋白质特异性功能化。随后，电输运测量将在这些纳米隙器件上进行，作为栅极电压的函数，在不同的温度下，以及在适用的情况下，作为照明的函数。此外，先进的表征方法，如非弹性电子隧穿光谱，将补充基本的电荷输运研究。我们将在现有的框架内分析和建模我们的电数据，随着它们变得可用，可能新的理论模型通过固体电极接触的蛋白质进行电荷传输。我们期望我们的工作将为理解蛋白质中复杂电荷传输场景提供急需的数据，并最终将与未来在生物电子学领域的应用相关，包括传感、能量转换和信息存储。

In this project we want to answer the question "(how) can gating control the efficiency and the mech-anism of electron transport across proteins?". Much knowledge and understanding has accumulated on charge transfer processes in several proteins. There is also growing interest in charge transport through proteins in solid state-type junctions. Still, there are very central open questions concerning what appears to be remarkably efficient charge transport and its temperature-(in)dependence, ques-tions that impact directly the issue of what is/are the underlying transport mechanism(s). As known from other areas of electronics, use of a 3rd electrode in a solid-state architecture can allow con-trolled electrostatic 'gating' of charge transport (as in field-effect transistors). Finding ways to repro-ducibly add gating will be a huge step towards answering these open questions and unraveling elec-tron transport across proteins. With a gate the protein molecular electronic energy level distribution may be shifted w.r.t the leads Fermi levels, for correlation with the corresponding transport process-es. We intend to achieve the abovestated goal to allow tackling the fundamental issue of transport mechanisms technically by realizing different architectures of highly doped silicon contacts which are separated by a few up to ~ 10 nm, only (nanogap electrodes), and which feature a gate electrode in close proximity. We will use selected, suitable protein systems and after characterizing these thoroughly on planar surfaces such as those of same material as the electrodes, the nanogaps shall be specifically functionalized with these proteins. Subsequently, electrical transport measurements will be carried out on these nanogap devices as function of gate voltage, at varying temperatures and where applicable, as function of illumination. Additional, advanced characterization methods such as inelastic electron tunneling spectroscopy will complement the fundamental charge transport stud-ies. We will analyze and model our electrical data within the framework of existing and, as they be-come available, possibly new, theoretical models of charge transport through proteins contacted by solid-state electrodes. We expect that our work will provide muchneeded data, required to under-stand the complex charge transport scenarios in proteins, and eventually will become relevant for future applications in the field of bioelectronics including sensing, energy conversion and information storage.